1. Field of the Invention
This invention relates to a cushion arrangement for a seat, a bed, or the like. Specifically, this invention relates to a cushion arrangement for a seat, a bed, or the like in means of transportation including vehicles, vessels, and aircrafts.
2. Description of the Prior Art
Japanese published examined utility model application 60-31549 discloses a vehicle seat, the seat cushion of which defines a chamber accommodating cushioning members. This chamber is in constant communication with atmosphere via first-type slits. The chamber can communicate with atmosphere also via second-type slits. Check valves block and unblock the second-type slits to control a damping factor. During appreciable contraction of the chamber, the check valves unblock the second-type slits and reduce resistance to the escape of air from the chamber to atmosphere so that a decreased damping factor is induced. During expansion of the chamber or during small variations in volume of the chamber, the check valves block the second-type slits and increase resistance to the admission of air into the chamber so that an increased damping factor is induced.
Japanese published unexamined utility model application 57-100536 discloses a vehicle seat, the seat cushion of which defines a chamber accommodating a cushioning member. This chamber communicates with atmosphere via holes having adjustable cross-sectional areas. A damping factor depends on the cross-sectional areas of the communication holes. A sensor detects the frequency of vibration of the vehicle body relative to a vehicle axle. The cross-sectional areas of the communication holes are adjusted in accordance with the detected vibration frequency so that the damping factor varies as a function of the vibration frequency.